1. Field of the Invention
The invention relates to a lamp unit used for a vehicular headlamp.
2. Description of Related Art
Vehicular headlamps, in which semiconductor light emitting elements, such as light emitting diodes (LEDs), are used as the light sources, have already been available. Japanese Patent Application Publication No. 2005-108554 (JP-A-2005-108554), for example, describes a lamp unit for a vehicular headlamp, in which first and second semiconductor light emitting elements are arranged back to back. In this lamp unit, the light from the first semiconductor light emitting element and the light from the second semiconductor light emitting element are reflected by a first reflector and a second reflector, respectively, that are provided, relative to the first and second semiconductor light emitting elements, in the directions of the light emission of the first and second semiconductor light emitting elements, toward the vicinity of the light source-side focal point of the projection lens and are thrown ahead of the vehicle through the projection lens.
When the first and second semiconductor light emitting elements are arranged back to back as in the case of the lamp unit described in JP-A-2005-108554, however, the light unit can become large because of the presence of the first and second reflectors.